Low-drive-voltage Ti: LiNbO3 Mach-Zehnder modulator using a coupled line

T. Namiki*, N. Mekada, H. Hamano, T. Yamane, M. Seino, Hirochika Nakajima

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


A modulator that uses a coupled line as a traveling-wave electrode to reduce the drive voltage is discussed. For modulation, complementary signals with equal amplitude and 180° out of phase are applied to the coupled line. The modulator was fabricated on a z-cut LiNbO3 wafer for use at 1.55 μm. Wavegiudes were formed by diffusing 90-nm-thick, 7-μm-wide Ti stripes for 8 h 1050°C in wet O2. The 500-nm-thick SiO2 buffer layer was formed by electron-beam evaporation. The coupled line used plated gold electrodes 9 μm wide, 5 μm thick, and 20 mm long. The two lines were 12 μm apart. The drive voltage is 27 V at 100 Hz. The insertion loss of the microwave energy increases slowly as the frequency rises. It is -3 dB at 2.5 GHz and -6 dB at 10 GHz. The 3-dB bandwidth of the modulation response exceeds 5 GHz. The bandwidth is limited by the loss of microwave energy and velocity mismatch. It can be expanded by optimizing the coupled linear structure and using a thicker buffer layer and electrodes. This modulator shows promise for use in broadband and low-drive-voltage modulation.

Original languageEnglish
Title of host publicationTechnical Digest Series
Place of PublicationWashington, DC, United States
PublisherPubl by Optical Soc of America
Number of pages1
ISBN (Print)1557521123
Publication statusPublished - 1990
Externally publishedYes
Event1990 Optical Fiber Communications Conference - OFC'90 - San Francisco, CA, USA
Duration: 1990 Jan 221990 Jan 26


Other1990 Optical Fiber Communications Conference - OFC'90
CitySan Francisco, CA, USA

ASJC Scopus subject areas

  • Engineering(all)


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